If you want them to celebrate Valentine's Day and have some silly love triangle with a foreign dude, then for the love of all things holy and for the sake of my sanity, can't you just make it modern?! Gosh darn it, is it so hard to keep some authenticity of the period? You know, that's kind of the whole point of the period drama?? There's artistic license, and then there's pure gratuitousness. This is gratuitous, with a plastic bow on top.